It generally is recognized that fabrics comprising synthetic polymeric fibers, such as polyethylene terephthalate fibers, have an undesirable propensity upon prolonged use to exhibit small compact groupings of entangled fibers (i.e., fuzz balls) on the fabric's surface. Such fiber groupings commonly are termed "pills" and tend to form and to tenaciously adhere to the surface of the fabric as the fabric encounters surface abrasion during normal use. The aesthetic appearance of the fabric accordingly may be adversely influenced by these relatively compact groupings of entangled fibers which are retained on the surface of the fabric.
Heretofore, it has been believed that such pills can be traced to the relatively high strength of the synthetic fibers present in the fabric. For instance, the pills may be more or less permanently attached to the fabric's surface by one or a few synthetic polymeric fibers extending out of the fabric which will resist breakage as surface abrasion continues. This theory of pill formation is supported by the general lack of the retention of undesirable fuzz balls on the surface of a fabric consisting solely of cotton fibers following the same surface abrasion conditions. It is believed, for instance, that any entangled cotton fibers which form at the surface of the fabric readily break away since the cotton fibers are of an inherently lesser strength.
This pilling problem may be observed in fabrics formed in whole or in part from polyethylene terephthalate fibers which are either in a staple or in a continuous configuration. Pills commonly are observed on fabrics formed from blends of cotton fibers and staple polyethylene terephthalate fibers following extended use. While the pills may be observed in fabrics having a wide variety of constructions, they frequently are observed on knitted fabrics which comprise polyethylene terephthalate fibers.
One approach heretofore proposed to reduce the tendency of the polyethylene terephthalate fibers to pill is initially to limit the intrinsic viscosity of the polyethylene terephthalate prior to fiber formation. Such reduced intrinsic viscosity provides a general indication of reduced polymeric chain length and leads to fibers having a lesser strength. Accordingly, when such entangled fibers become free on the surface of the fabric following abrasion, they tend to cleanly break away more readily and do not serve as a secure link which retains a fuzz ball at the surface of the fabric. It has been found, however, that when this approach is followed, it is more difficult initially to form and to process the polyethylene terephthalate fibers into a fabric using standard processing conditions because of their reduced strength. Such reduced strength can lead to premature fiber breakage with the concomitant processing disadvantages.
In U.S. Pat. Nos. 3,104,450; 3,576,773; 3,580,874; 3,607,804; 3,991,035; and 4,004,878 are proposed the incorporation of certain moieties in the backbone of polyethylene terephthalate fibers in an effort to improve pilling characteristics.
In U.S. Pat. Nos. 3,834,868 and 4,270,913 is proposed the degradation of previously formed polyethylene terephthalate fibers in an effort to reduce the propensity of the fibers to pill.
In U.S. Pat. Nos. 2,897,042; 4,071,502; and 4,359,557 are disclosed techniques for drawing or shrinking polyethylene terephthalate fibers under specified conditions in order to reduce the tendency to pill.
It is an object of the present invention to provide an improved process for the production of a fabric comprising polyethylene terephthalate fibers having a reduced tendency to pill and otherwise satisfactory performance characteristics.
It is an object of the present invention to provide an improved process for the production of a fabric comprising polyethylene terephthalate fibers having a reduced tendency to pill wherein the fibers can be melt-extruded and fabrics formed therefrom using conventional technology.
It is another object of the present invention to provide improved polyethylene terephthalate fibers having a reduced tendency to pill.
It is another object of the present invention to provide an improved process for the production of a dyed fabric comprising polyethylene terephthalate fibers having a reduced tendency to pill which can be carried out on a relatively economical basis.
It is a further object of the present invention to provide an improved polyethylene terephthalate fabric having a reduced tendency to pill wherein the polyethylene terephthalate fibers are more hydrophilic in nature which renders them more wettable and improves their stain release characteristics.
These and other objects, as well as the scope, nature, and utilization of the present invention will be apparent to those skilled in the art from the following detailed description and appended claims.